<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
<style type="text/css">
body{
  border:1px solid balck;
  width: 800px;
  height: 400px;
  background-repeat:no-repeat;
  background-image: url("img/welcom.jpg");
}
</style>
</head>
<body>
  <div style="margin-top:300px;margin-left: 310px">
                    <h2>欢迎使用教学管理平台</h2>
  </div>
</body>
</html>